Glasses are essential for a large percentage of both children and adults. The glasses can be prescriptive to correct a visual defect, sunglasses to reduce eye fatigue and irritation from a bright sun, or both. Because of varying requirements, a person can own many pairs of glasses. This is expensive and can also be inconvenient. For example, a nearsighted person often carries both clear and tinted glasses. Sunglasses offer a wide variety of options as well. Some have a gray tint which merely reduces the amount of light transmitted to the eye. Other lenses can be tinted yellow to improve the visual contrast experienced by the wearer. Others prefer brown or even rose colored tints. Likewise, a single lens can be placed with various frame colors.
A need exists for a frame that allows the wearer to exchange lenses. The frame should provide a secure mount for the lens while also allowing its easy removal. U.S. Pat. No. 5,467,148 to Conway discloses an example of a frame system that allows for interchangeable lenses. The frame has a top frame and a rotatable nose piece. The nose piece has large lateral grooves. Two lenses are specially designed to engage the frame and nose piece. Each lens has two projections that fit notches in the frame. In other words, the system uses four separate pieces. If any one piece is damaged or lost, then the system will not work. Likewise, if the projections from either lens is broken, then the lens will not securely engage the frame. A need exists for a simpler frame system that provides the user with a secure method of attaching the lens to the frame.